QURATULAIN MUGHALBATCH IVDOTOR OF PHYSICAL THERAPYISRA UNIVERSITY

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These are drugs that promote defecation. They are also called laxatives and cathartics. Laxatives have milder action while cathartics

or purgatives have more powerful action.

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CLASSIFICATION

Bulk laxatives

Fecal softeners

Osmotic purgatives

Stimulant purgatives

Absorbs water to increase bulk. Distends bowel to initiate reflex bowel activity. These include vegetable fiber and other

substances that are not digested but increase the volume of intestinal contents forming a large, soft, sold stool.

Dietary fiber consists of cell walls and other parts of the fruits and vegetables that are unabsorbable.

Adding fiber to the diet is a safe and natural way of treating constipation in persons who are on low-fiber diet.

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Bran is the residue left when flour is made from cereals and contains 40% fiber-but is unpalatable.

Ispaghula and plantago seeds contain natural mucilage which absorb water to form a gelatinous mass and are more palatable than bran.

Methylcellulose is a semisynthetic derivative of cellulose. Adequate water should be taken along with bulk laxatives.

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Docusate sodium (dioctyl sodium sulphosuccinate) softens feces by lowering the surface tension of the intestinal contents. This allows more water to be retained in the feces which become soft.

Liquid paraffin(emollients) is a mineral oil that is not digested. It lubricates and softens feces. It is unpalatable; aspiration may cause lipoid pneumonia; it may leak out of the anus causing discomfort. Hence not preferred.

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These are solutes that are not absorbed in the intestine, osmotically retain water and increase the bulk of intestinal contents. They increase peristalsis and expel a fluid stool.

Magnesium hydroxide, magnesium sulphate, sodium potassium tartrate, sodium sulphate, and phosphate are some inorganic salts used as osmotic or saline purgatives. They are used to prepare the bowel before surgery and in food poisoning.

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Lactulose is a synthetic disaccharide that is not absorbed, holds water and acts as an osmotic purgatives.

Flatulence and cramps may be accompanied. In the colon, lactose is fermented to lactic and acetic acids which inhibit the growth of ammonia-producing bacteria in the colon.

It also inhibits the absorption of ammonia by lowering the pH and thus lowers the blood ammonia level.

It is used in hepatic coma for this effect (hepatic coma is worsened by ammonia).

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They increase intestinal motility and increase the secretion of water and electrolytes by mucosa.

They may cause abdominal cramps. When cascara sagrada and senna (source

plants) are given orally, active anthraquinonesare liberated in the intestines which stimulates the myenteric plexus in the colon.

Evacuation takes 6-8hr. Long-term use cause melanotic pigmentation of the colon.

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STIMULANT

PURGATIVES

PHENOLPHTHALEIN BISACODYL CASTOROIL

It is an indicator, acts on the colon after 6-8hrs to produce soft, semiliquid stools.

It undergoes enterohepatic circulation which prolongs its actions.

Allergic reactions including pink colored skin eruption and colic limit its use.

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It related to phenolphthalein is converted to the active metabolites In the intestines.

It can be given orally(5mg) but usually is used as rectal suppositories(10mg) which results in defecation in 15-30mints.

It is safe except that prolonged use may cause local inflammation.

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It is hydrolyzed in the upper small intestine to ricinoleic acid which is a local irritant and increase intestinal motility.

It is a powerful and one of the oldest purgatives.

Stool is semi-liquid and is accompanied by gripping.

It is not preferred.

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PHARMACOLOGY FOR PHYSIOTHERAPIST

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